All devices on the Web are recognized by a special number called an IP address, such as 123.123.123.123. If you have a website, the domain that you enter to be able to open it is for your convenience, but the server where your site files are still has an IP. As there are a lot more websites and devices than there are IP addresses, all shared web hosting servers have a number of websites under an identical IP, whereas using a dedicated server you will have a dedicated IP as well. Even in the first case though, you can get a dedicated IP for your websites and host them on a shared server. One benefit would be that you'll get better search engine positions since a dedicated IP generally means a faster loading website. Furthermore, you need such an IP when you plan to purchase an SSL certificate for your website and shield the data that visitors submit on it.